Scientific english for food science

Reading Food science can be defined as the application of the basic sciences and engineering to study the fundamental physical, chemical, and biochemical nature of foods and the principl

BỘ GIÁO DỤC VÀ ĐÀO TẠO

ĐẠI HỌC THÁI NGUYÊN

TRƯỜNG ĐẠI HỌC NÔNG LÂM

NGUYỄN HỮU NGHỊ

SCIENTIFIC ENGLISH

FOR FOOD SCIENCE

THÁI NGUYÊN 2011

UNIT 1 INTRODUCTION TO FOOD SCIENCE

1 Reading

Food science can be defined as the application of the basic sciences and engineering to study the fundamental physical, chemical, and biochemical nature of foods and the principles of food processing Food technology is the use

of the information generated by food science in the selection, preservation, processing, packaging, and distribution, as it affects the consumption safe, nutritious and wholesome food As such, food science is a broad discipline which contains within it many specializations such as in food microbiology, food engineering, and food chemistry Because food interacts directly with people, some food scientists are also interested in the psychology of food choice.Industry and academic specialists have often differed about the definition of the term food scientist, and what should constitute appropriate formal training Similarly, the major schools offering a degree in food science have not always agreed on the requirements for such a degree The Education Committee of the Institute of Food Technologists (IFT) adopted a set of minimum standards for a university undergraduate curriculum in food science These standards are followed by most universities which offer degrees in food science and reflect the scientific nature of food science The most recent recommended minimum standards include both basic science courses and core food science and technology courses for B.S degree The standards are based on a 120 – semester – hour or 180 – quarter – hour requirement for graduation Courses should carry three to five semester hours or four to eight quarter hours of credit

The core food science and technology courses, representing a minimum of 24 semester hours or 36 quarter hours including:

Food chemistry covers the basic composition, structure, and properties of foods and the chemistry of changes occurring during processing and utilization Prerequisites should be courses in general chemistry, organic chemistry, and biochemistry

Food analysis deals with the principles, methods, and techniques necessary for quantitative physical and chemical analyses of food products and ingredients The analyses should be related to the standards and regulations for food processing Prerequisites include courses in chemistry and one course in food chemistry

Food microbiology is the study of the microbial ecology related to foods, the effect of environment on food spoilage and food manufacture, the physical,

chemical, and biological destruction of microorganism in foods, the microbiological examination of food stuffs, and public health and sanitation microbiology One course in general microbiology is the prerequisite.

Food processing covers general characteristics of raw food materials; principles

of food preservation, processing factors which influence quality, packaging, water and waste management, and good manufacturing practices and sanitation procedures

Food engineering involves study of engineering concepts and unit operation used in food processing Engineering principles should include material and energy balances, thermodynamics, fluid flow, and heat and mass transfer Prerequisites should be one course in physics and two in calculus

Process (n) Chế biến, quá trình

Preservation (n) Bảo quản

Packaging (n) Đóng gói, bao gói

Distribution (n) Phân phối

Consumption (n) Sự tiêu thụ

Nutrition (n) Dinh dưỡng

Discipline (n) Lĩnh vực

Specialization (n) Chuyên môn hoá, chuyên môn

Industry (n) Công nghiệp

Academy (n) Hoc thuật

Institute (n) Viện nghiên cứu

Standard (n) Tiêu chuẩn

Undergraduate (n) Sinh viên đại học nhưng chưa tốt nghiệpCurriculum (n) Chương trình học

University (n) Trường đại học

Bachelor degree (n) Bằng đại học

Quantitative (adj) Định lượng

Ingredient (n) Thành phần

Regulation (n) Nội quy, quy định

Ecology (n) Sinh thái học

Spoilage (n) Hư hỏng, thối hỏng

Answer the following questions:

1 Give the definition of food science?

2 What does food science contain?

3 What does food chemistry cover?

4 What does food analysis deal with?

5 What does food microbiology study?

6 What does food processing concern about?

7 What does food engineering involve?

8 Which aspects of food science are you interested in? Why?

UNIT 2 INTRODUCTION TO MODIFIED ATMOSPHERE

PACKAGING

1 Reading

Modified atmosphere packaging (MAP) can be defined as the enclosure of food products in a barrier film in which the gaseous environment has been changed or modified to slow respiration rates, reduce microbiological growth and retard enzymatic spoilage with the intent of extending shelf life There are two methods for MAP, modified atmosphere (MA) and controlled atmosphere (CA)

In MA, the atmosphere inside package containing a respiring product changes with time due to the consumption of oxygen and production of carbon dioxide that occurs as a result of the respiration process, until eventually an equilibrium concentration of these gases is established in the atmosphere within the package The equilibrium concentrations of these gases in the package headspace is governed by a complex function of the intrinsic respiration rate of the product, the weight of product in the package, and the permeability characteristics of the package to these gases The intrinsic respiration rate of the products and the permeability characteristics of the package increase with temperature, and so can potentially vary considerably over the storage life of the product, depending on the integrity of the cold chain during storage and distribution of the packaged product

In CA, the initial headspace gases will be rapidly replaced with a gas composition that has a concentration of oxygen and carbon dioxide that is closer to the optimal levels (2 to 5% oxygen/3 to 10% carbon dioxide) in order

to avoid prolonged exposure of the product to suboptimal headspace gas concentrations This can be achieved by simply flushing the package headspace with a suitable gas mixture; however, more recently chemical approaches have been reported that have the commercial advantage of potentially providing

a means of avoiding the slow and costly gas-flush step

An example of Litchi

Litchi (Litchi chinensis Sonn.), native to southern China, is adapted to the warm

subtropics, cropping best in regions with brief cool dry frost-free winters and long hot summers with high rainfall and humidity The fruit easily loses its commercial value after harvest due to pericarp browning, quality deterioration and decay (Ray, 1998) Browning of litchi pericarp is still considered to be a

major problem affecting its market value During the past two decades, a considerable amount of research work has been carried out on litchi fruit, including analyzing the role of pigments, hormones and some other closely related factors responsible for postharvest browning of litchi fruit, selecting suitable storage temperature and postharvest chemical treatments to prevent browning, control decay and extend storage life Browning of litchi pericarp was thought to be due to degradation of anthocyanidin by polyphenol oxidase (PPO) and peroxidase (POD) and was primarily the result of PPO activity degrading the anthocyanins and producing brown-coloured by-products Since PPO can not oxidize monophenols on odiphenols, the POD was also suggested to play an important role in the browning of litchi pericarp In general, sulfur dioxide treatments have been widely used to control saprophytic surface fungi and prevent peel browning of litchi fruit.

MAP has been considered to be beneficial to maintain high humidity, essential for prevention of water loss and browning of litchi pericarp CA with low-O2 and high-CO2,have been successfully used to reduce decay, maintain quality and extend storage life in many fruits In recent years, high O2 treatment was considered to be effective in inhibiting enzymic discoloration, preventing anaerobic fermentation reactions, and limiting aerobic and anaerobic microbial growth

2 Vocabularies

Modified (adj) Cải biến

Controlled (adj) Kiểm soát

Atmosphere (n) Khí quyển

Packaging (n) Bao gói

Enclosure (n) Ngăn cản, rào cản

Film (n) Màng

Respiration (n) Hô hấp

Spoilage (n) Sự hư hỏng của thực phẩm

Extending (n) Kéo dài

Shelf life (n) Thời gian bảo quản

Modification (n) Sự cải biến

Consumption (n) Sự tiêu thụ

As a result of (clause) Do kết quả của cái gì

Equilibrium (n) Cân bằng

Establish (v) Thiết lập được

Headspace (n) Vùng khoảng không phía trên nông sảnPermeability (n) Khả năng thấm khí

Integrity (n) Tính toàn bộ, toàn vẹn

Composition (n) Thành phần, hợp phần

Prolonged (adj) Kéo dài

Exposure (v) Phơi bày, để cho tiếp xúc

Postharvest (n, adj) Sau thu hoạch

Degradation (n) Sự phân huỷ

Anthocyanin (n) Anthocyanin

Saprophytic (adj) Hoại sinh

Fungi (n) Nấm mốc

Humidity (n) Độ ẩm

Anaerobic (adj) Yếm khí

Aerobic (adj) Hảo khí

Fermentation (n) Lên men

3 Exercises

Answer the following questions

1 Give the definition of MAP?

2 Why does the atmosphere inside package change?

3 What is the equilibrium concentration of the gases in the package headspace governed?

4 What is the optimal gas composition for CA?

5 What are the main differences between CA and MA?

UNIT 3 INTRODUCTION TO STARCH MODIFICATION

Starch can be physically modified to improve water solubility and to change particle size The physical modification methods involve the treatment of native starch granules under different temperature/moisture combinations, pressure, shear, and irradiation Physical modification also includes mechanical attrition to alter the physical size of starch granules Starch is widely modified by chemical methods The most common chemical modification processes are acid treatment, cross-linking, oxidation, and substitution, including esterification and etherification

Chemical modification

The most common chemical modification includes: oxidation, esterification, and etherification The chemical modification of starch results in enhanced molecular stability against mechanical shearing, acidic, and high temperature hydrolysis; obtaining desired viscosity; increasing interaction with ion, electronegative, or electropositive substances; and reducing the retrogradation rate of unmodified starch

Physical modification

Physical modification of starch can be applied alone or with chemical reactions

to change the granular structure and convert native starch into cold water soluble starch or into small crystallite starch Cold water soluble starch is prepared by pregelatinization of native starch slurry, followed by drum drying Because of

pregelatinization and drying, the granular integrity is lost and paste viscosity of starch is reduced Therefore, the modified starch is cold water soluble

Heat-moisture and annealing treatments induce the rapid migration or rearrangement of the amylose molecules in the granules to form intermolecular bonds between the amylose molecules and/or between the amylase molecules and the amylopectin molecules

Extrusion modification of starch is a process that uses the molten phase of high solid concentration to transform starch while maintaining a macromolecular structure

2 Vocabularies

Starch (n) Tinh bột

Modify (v) Biến đổi, biến hình

Modification (n) Sự biến đổi, sự biến tính

Solubility (n) Khả năng hoà tan

Viscosity (n) Độ nhớt

Thickening power (n) Khả năng làm đầy, khẳ năng làm đặc

Gelatinization (n) Quá trình hồ hoá, hồ tinh bột

Retrogradation (n) Sự thoái hoá hồ tinh bột

Syneresis (n) Sự chảy dịch, tách nước

Hydrophobic (adj) Kỵ nước

Hydrophilic (adj) Ưa nước

Esterification (n) Este hoá

Etherification (n) Ete hoá

Hydrolysis (n) Thuỷ phân

Electronegative (adj) Mang điện âm

Electropositive (adj) Mang điện dương

Crystalline (adj) Kết tinh, tinh thể

Pregelatinization (n) Hồ hoá trước (hồ hoá sơ bộ)

Answer the following questions

1 What are the disadvantages of native starch?

2 What can modify functionality of starch?

3 What does the modification alter the properties of starch?

4 What is another purpose of starch modification?

5 What does physical modification method involve?

6 What are the most common chemical modification processes?

UNIT 4 CARBON SOURCES FOR MICROORGANISIM NUTRITION

1 Reading

A carbon source is necessary to provide the cell with energy as well as the material with which to grow and synthesise arrange of primary and secondary metabolites The best energy source depends on the type of organism utilised, e.g autotroph, chemotroph, etc

There is obviously a wide range of carbon sources and the one chosen should be appropriate to the organism but also to the economics of the process

At research scale the latter tends to be less important, but it should be borne in mind if the objective of the program is to develop an industrially relevant process This section will look at several carbon sources and indicate the advantages and disadvantages of each A typical microorganism is approximately 50% carbon, making carbon the most significant substrate and care should be taken to ensure that the carbon concentration does not become limiting The yield of biomass on carbon is approximately 0.5, which means that

if a biomass concentration of 50 gL−1 is required, 100 gL−1 of the carbon source must be supplied, although not necessarily all at once if fed-batch culture

is being utilised

The great majority of laboratory and industrial fermentations tend to use a very limited range of easily utilisable substrates to supply the energy and C requirements of cultures This does not imply that other C and energy sources could not be used, just that this limited range is usually available and methods for preparing and analysing the consumption rates of such substrates are well understood The production of pharmaceuticals, especially biopharmaceuticals

by fermentation, takes place in the context of an industry that is, with the possible exception of the nuclear industry, perhaps the most regulated in the world This fact accounts for a degree of ‘conservatism’ in terms of nutrient supply

Glucose

Glucose is universally acceptable for growth of most cell lines, for instance

in animal, plant or microorganisms Supplied as a powder in the pure form, the substrate is readily available, reliable, easily stored, easily handled and has no significant implications for health and safety These qualities make glucose a popular choice of carbon source There some drawbacks to using glucose, notably: